There has been a demand for marking at a higher speed by a laser marker in recent years. A technique for attaining a higher speed of this kind is disclosed, for example, in Japanese Patent Application Laid-Open No. 2-268988. According to that technique, the display plane of a liquid crystal mask is divided into upper and lower halves in a laser marker. Upon the completion of the scanning of an upper half and the initiation of the scanning of a lower half, the replacement of a pattern of marking for the upper half is also initiated.
The aforesaid technique surely improves the speed of pattern replacement, but does not contribute anything to the attainment of a higher speed in terms of time required for scanning because scanning itself is executed over an entire image plane.